1711 展伸マグネシウム合金の応力制御低サイクル疲労挙動に及ぼす変形異方性の影響(OS17-3 低サイクル疲労とその応用-規格化、多軸・異方性の検討-)

概要

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Extruded magnesium alloy shows mechanical anisotropy caused by the limitation of slip system in hcp lattice structure and texture formed by extrusion. In order to investigate an effect of the anisotropy on fatigue deformation and fatigue lifetime of extruded magnesium alloys, stress controlled low-cycle fatigue tests have been performed at room temperature and in ambient atmosphere using smooth round bar specimens of AZ31, AZ61 and AZ80. Compressive mean strain occurred under the low-cycle fatigue process depending on stress amplitude levels and tested alloys due to asymmetry of tensile yield stress and compressive one because of active twinning under compressive loading. Exponent α and coefficient C in the Coffin-Manson law was related with compressive yield stress of each alloy. An energy-based concept considering the mean strain effect was successfully predicted the stress controlled low-cycle fatigue lifetime.
2010-10-09